*{
	margin: 0;
	padding: 0;
}
.center{
	position: absolute;
	width: 400px;
	height: 200px;
	background-color: #ccc;
	top: 50%;
	left: 50%;
	transform: translate(-50%, -50%);
	overflow: hidden;
}
.lefttop{
	position: absolute;
	width: 50px;
	height: 50px;
	top: 0px;
	left: 0px;
	background-color: #fc0;
	border-radius: 0 0 100% 0; 
}
.rightbottom{
	position: absolute;
	width: 50px;
	height: 50px;
	bottom: 0px;
	right: 0px;
	background-color: #fc0;
	border-radius: 100% 0 0 0; 

}